This invention relates generally to a venting system and method for use in a double-tube xe2x80x9cslip-in-tubexe2x80x9d driveshaft. The concept of a double-tube xe2x80x9cslip-in-tubexe2x80x9d splined driveshaft is relatively new.
Applicant owns U.S. Pat. No. 6,279,221 (xe2x80x9cthe ""221 patentxe2x80x9d), issued Aug. 28, 2001, for a double-tube xe2x80x9cslip-in-tubexe2x80x9d vehicle driveshaft, which is hereby incorporated in full by reference. A double-tube xe2x80x9cslip-in-tubexe2x80x9d splined driveshaft comprises first and second members each having splined portions. The second member is telescopically resident within the first member, and the splined portion of the first member cooperates with the splined portion of the second member. In such manner, the first and second members cooperatively form the driveshaft. The cooperating splined portions of the first and second members allow external elements to protrude into the double-tube splined driveshaft at the location of the intermeshing splines.
A slip-in-tube driveshaft contains, depending on diameter and length, 8 to 16 liters of air sealed inside it during assembly. Driveshaft working temperature varies continuously depending on ambient temperature, driving conditions, momentary torsional load, and depth and frequency of driveshaft plunging action. Those temperature changes affect the internal air pressure inside the driveshaft tube. In addition, the air column inside the tube experiences compression and decompression by reversing, at various frequencies, plunging motions of the driveshaft. Those factors cause, at certain frequencies, the air column inside the tube to vibrate and resonate within the shaft, thereby creating driveshaft noise and boom. This can be a potentially serious problem by degrading driveline noise, vibration, and harshness (NVH) performance. In addition, the air inside the tube can create hydraulic lock, impeding plunging action, and also resisting manual driveshaft length adjustment for its installation during vehicle final assembly. This can make the installation of the shaft difficult.
Venting is necessary to continually equalize the internal driveshaft pressure with that of the atmosphere. At the same time, it is necessary to prevent external elements, such as water, dirt, or salt, from entering the interior of the driveshaft, thereby causing premature wear or corrosion.
It is in general an object of the invention to provide a venting system and venting method for a double-tube xe2x80x9cslip-in-tubexe2x80x9d splined driveshaft.
In one aspect, this invention provides a venting system for a driveshaft, wherein the driveshaft comprises first and second members each having splined portions, the second member is telescopically engaged with the first member, and the splined portion of the first member cooperates with the splined portion of the second member thereby allowing the first and second members to cooperatively form the driveshaft. The venting system comprises at least one vent defined in the driveshaft for allowing air outside the driveshaft to pass into at least one of the first and second members, and a plug mounted over at least one vent defined in the driveshaft.
In another aspect, this invention provides a venting system for a splined driveshaft comprising a weld yoke at an end of the splined driveshaft, at least one vent defined in the weld yoke allowing air outside the splined driveshaft to pass into the splined driveshaft, and a plug mounted over at least one vent.
In yet another aspect, this invention provides a method of venting a splined driveshaft. The method comprises providing a splined driveshaft, forming at least one vent defined in the splined driveshaft, mounting a plug over at least one vent in the splined driveshaft, and venting the splined driveshaft through at least one vent.
The present invention, together with further objects and advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.